1. Field of the Invention
The present invention relates to proteins produced by human lymphocytes and, in particular, to a protein expressed at the surface of the latter, DNA sequences coding for these proteins and the pharmaceutical and biological uses of these proteins.
2. Description of the Related Art
A certain number of protein structures of the cell surface "belong" to the "superfamily" of the immunoglobulins (IgSF). This family of molecules includes the proteins comprising at least one domain with a characteristic folding region called the Ig fold. Several of these molecules have essential functions in immune responses.
In addition to ensuring specific antigen recognition, as do for example the immunoglobulins and the T receptors, they may function as monomorphic ligands critical in cell-cell interactions (for example ICAM, CD4, CD8), receptors for viruses (for example CD4, ICAM) or receptors for the lymphokines (for example IL1-R, IL6-R).
The discovery and characterization of the membrane proteins expressed on the lymphocytes have been facilitated by the development of genetic engineering techniques. By means of various experimental techniques, this methodology makes it possible to characterize the genes coding for the proteins and hence to deduce the peptide sequence from knowledge of the nucleotide sequence of the gene. Other applications of these genetic engineering techniques based on the same experimental principles enable virtually unlimited quantities of the proteins corresponding to the genes which have been discovered to be produced as a consequence of procaryotic or eucaryotic systems of expression.